Acoustic implosion generators for producing in water acoustic impulses are known. U.S. Pat. No. 3,369,627 shows a generator wherein a cavity is created between two rapidly separating plates. The violent collapse of this cavity by the surrounding water generates an acoustic impulse which propogates throughout the body of water.
U.S. Pat. No. 3,642,090 shows a generator having a piston moving away from a liquid body faster than the liquid body can follow the piston. A cavity is formed between the piston and the surrounding liquid body. The surrounding liquid rushes in to fill this cavity and in so doing a high-power acoustic impulse becomes generated in the liquid body.
Similar generators are described in U.S. Pat. Nos. 3,642,089 and 3,711,824.
A new implosion generator, known as a "WATER GUN.RTM.", is described in French Pat. Nos. 72,14513 and 73,15317 and in Ocean Industry, pages 42-43, July, 1973.
The known implosion generators have had very limited commercial success because of the inherent drawbacks in their mechanical constructions, of their poor "pressure signatures", and for other reasons which will become apparent from the following description.
This invention is an improvement on such implosive generators and especially on the WATER GUN primarily in that it allows an automatic return stroke of the gun's piston, it eliminates the recoil of the gun, and most importantly it substantially reduces or completely suppresses the bubble effect produced by known implosive generators.